A diagnosis is made via a medical professional’s evaluation and tests to check for problems due to anorexia nervosa.
Because individuals (generally) do not think they have a problem, they resist evaluation and treatment. Usually, they are brought to see a medical professional by family members, or they come because of another disorder.
Medical professionals measure height and weight and use the results to calculate the body mass index (BMI).
They also ask individuals how they feel about their body and weight and whether they have other symptoms. They may use questionnaires developed to detect eating disorders.
Medical professionals also check for other disorders that can cause weight loss or a reluctance to eat, such as schizophrenia, depression, disorders that interfere with the absorption of food (malabsorption), amphetamine abuse, and cancer.
If individuals have the following, anorexia nervosa is likely:
- Restriction of eating that results in a low body weight, usually with a BMI of less than 17:
- For children, a BMI less than the 5th percentile for their age or less than what is expected based on prior growth.
- Fear of obesity.
- A distorted body image and/or denial that they have a serious disorder.
Anorexia nervosa may be diagnosed in children and adolescents who have not lost weight but have not grown as expected because they restrict their food intake.
Medical professionals also do a physical examination and blood and urine tests to check for effects of weight loss and under-nutrition. A bone density test may be done to check for loss of bone density. Electrocardiography (ECG) may be done to check for abnormal heart rhythms.